The present invention relates to a deflecting diaphragm utilizing a brittle material diaphragm that deflects under pressure relative to a base plate and which is supported against damage when under high overpressures relative to the normal sensor range.
Semiconductor pressure sensors, which utilize a backing plate and a diaphragm that deflects under pressure, are known in the prior art. The deflection is measured in such prior art sensors in a number of ways, including capacitive sensing, and using strain gauges that are mounted on the diaphragm. The use of brittle material such as silicon, glass and quartz for diaphragms has also been known.
The need for protection of brittle material diaphragms when subjected to overpressure has been recognized. In general, such support has been obtained by resting the diaphragm surface across a facing surface of the base plate, which may be configured to match the deflected diaphragm configuration, so that when the diaphragm slightly exceeds its maximum design pressure sensing range it will be supported on the base. Preferably a substantial portion of the diaphragm will rest on a facing surface of the base. Recesses have been used in base plates and on diaphragms to attempt to ensure a full, continuous overpressure support across the deflecting portion of the diaphragm.